1. Field of the Invention
This invention relates to fluid conductors and more particularly a valve interposed in a fluid flow line for monitoring fluid pressure.
2. Description of the Prior Art
The most pertinent patent is believed to be U.S. Pat. No. 5,067,511, issued Nov. 26, 1991 to Taylor for High Pressure Emergency Fluid Shutoff Valve.
This patent discloses a valve body having a flow passageway interposed in a fluid conducting line. A valve having a head portion substantially greater in diameter than it's stem portion is slidably supported by the valve body. The valve head is normally maintained unseated in an upstream direction by a collapsible pin axially interposed between a valve cage and the end of the valve stem opposite it's head. In the event the downstream end of the flow line is closed, pressure build up in the valve body flow passageway forces the valve closed by collapsing the pin.
This invention similarly discloses a valve body having a flow passageway interposed in a fluid flow line, in which a valve is normally maintained off it's seat by a collapsible pin interposed between a valve cage and the end of the valve stem opposite it's head and fluid pressure on a valve stem piston. In the event downstream fluid pressure decreases below a predetermined value fluid flow against the valve head in combination with a valve stem spring collapses the pin and seats the valve head to close the flow passageway.